- HSAB-driven chemoselective N1-alkylation of pyrimidine bases and their 4-methoxy- or 4-acetylamino-derivatives
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The lithium salts of the conjugated bases of 4-methoxy- and 4-acetylamino-2(1H)-pyrimidinones 1-3 undergo highly chemoselective N1-methylation or ethylation when treated with methyl- or ethylsulfate (hard electrophiles) in dry dioxane, while the use of DMF as solvent results in competitive O2-alkylation. Potassium salts of the same bases in DMF undergo prevalent O2-attack. Under the same conditions, a similar but less chemoselective behaviour is observed in alkylation of thymine and uracil, where some N3-attack occurs. This can be rationalised in terms of the HSAB principle.
- Gambacorta, Augusto,Tofani, Daniela,Loreto, Maria Antonietta,Gasperi, Tecla,Bernini, Roberta
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p. 6848 - 6854
(2007/10/03)
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- Fluorinated Heterocyclic Compounds. 2. 2,4-Difluoro and 4-Amino-2-fluoropyrimidines, Nucleoside Base Analogs
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Nucleoside base analogs in which fluoro substituents replace the enolic hydroxy groups of uracil, thymine and cytosine have been prepared.Improved methods for the preparation and isolation of the known 2,4-difluoropyrimidine, 2,4-difluoro-6-methylpyrimidine and the new 2,4-difluoro-5-methylpyrimidine, 2-fluoro-4-aminopyrimidine, 4-fluoro-2-aminopyrimidine, and other alkylaminofluoropyrimidines are described.
- Svirskaya, Polina I.,Yedidia, Varda,Leznoff, Clifford C.,Miller, Jack M.
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p. 149 - 153
(2007/10/02)
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